Edgar Hooper responds : Aids ’began with virus from a chimp’

The world Aids epidemic began in Africa with the accidental infection of a human from a chimpanzee between 1915 and 1941, a US-based scientific team has claimed.

The claim, made in the latest issue of the journal Science, adds to the growing controversy over the origin of Aids, reignited by British journalist Ed Hooper in his book The River.

Mr Hooper argued that HIV-1, the main virus causing Aids, was first introduced accidentally into humans in the then Belgian Congo in the 1950s, as the result of trials of an experimental polio vaccine.

But the US researchers, led by Bette Korber of the Los Alamos laboratory in New Mexico, said that HIV-1 must have appeared before the vaccine trials.

The battle lines are now drawn before a showdown in London in September, when proponents of the conflicting theories will air their views at a Royal Society conference.

The Korber group used computers to analyse the recent rate of mutation of the most pernicious strain of HIV, HIV-1 M, which has infected 50m people and left 16m dead.

Working on the assumption that the original virus mutated into different versions at a steady rate over time, they tracked its first appearance in humans back to a point earlier than 1941 and later than 1915, most likely in 1931.

The experimental polio vaccine was given to hundreds of thousands of people in Central Africa between 1957 and 1960.

It is generally accepted that the first known case of HIV infection, retrospectively diagnosed, was from 1959, in Leopoldville, now Kinshasa

"Our analyses suggest that the HIV-1 M group ancestral sequence occurred decades before the vaccination programmes," said the group’s Science paper. "We find it unlikely that oral polio vaccine was the source of HIV-1 transmission to humans."

The Hooper scenario proposes that western scientists used the kidneys of chimpanzees, known to have been kept at a lab close to the city of Kisangani, to prepare the experimental vaccine, known as CHAT.

According to this theory, the kidneys contained a simian version of the HIV virus, SIV, which passed into some of those vaccinated. Cases of other viruses spreading via other polio vaccines are well documented.

Surviving members of the CHAT research team have said other primate kidneys, not organs from chimps, were used, but no paper evidence exists to say what exactly was done with the Kisangani chimps.

The Korber team acknowledged that they had not disproved the Hooper scenario, but said that to make their calculations wrong, the CHAT vaccine would have to have introduced nine genetically distinct versions of the HIV-1 virus into humans.

Mr Hooper said yesterday that he believed this was what had happened.

He pointed out that one key reference in the Korber paper, to one of the few surviving lab records from Kisangani, wrongly stated that the lab held only juvenile chimps, which would be less likely to harbour different types of SIV.

In fact the document, which is now in Mr Hooper’s hands and has been seen by the Guardian, records that at least one chimp was an adult.

Dr Korber and Mr Hooper present a contrast in styles ; the American scientist crunching numbers in a hi-tech lab ; the journalist relying on expertise picked up from years of poring over scientific journals.

"Dr Korber’s is an interesting theory, but doesn’t cast any light on how Aids began," said Mr Hooper.